Masturbation
helps relieve anxiety, stress, nervousness. In this role, at least in
the beginning, the self pleasing has nothing in common with sexuality
and can occur very early in life. Particularly in prepubertal girls,
masturbation can become a permanent activity of choice to soothe
everyday stress, compensate psychological traumas, etc. When puberty
comes, under pressure of developmental changes genital manipulation
becomes problematic, and girls of this age not rarely give up
masturbation as childish behaviour. Awakening sexuality together with
bouts of depression, uneasiness, uncertanity, typical for adolecent
non-infatuated and much more in infatuated mind, often make an
adolescent according to her own opinion a world champion of clitoral
stimulation by rubbing, humping, squeezing etc. Definitely, satisfying
sexual needs by induced with own fingers or hands free orgasms doesn't
put any burden on shoulders of a teenage girl or not-yet-married woman
which could be compared with consequences of premarital devirginization
and following sexual intercourses.

If you're that nervous, why don't you masturbate?
The Fury 1978, Dialogue Transcript